Heat-treatment of metals



Patented July 4, 1933 outrun stares-Parent than QHINTA MATSUNAWA,FUSATOSHI NOZAWA, AND MASUEIRO SUZUKI, GE TOKY'Q, J'APAN, ASSIGNORS TOKABUSHIKI 'KAISHA SUMITOMO SEXKOSHO, 0F @SAKA, JAPAN, A

' GQEEOBATION 0h JAPAN HEAT-TREATMENT 0E METALS l lo Drawing.application filed January 316, 1933, Serial lio; 852,096,, and in JapanFebruary 5, 1839,

This invention relates to improvements in heat-treatment of" metalswherein properly heated metals are quenched in a mixture of oil andwater.

The chief object of this invention is to obtain a process whereby thefinal efl'ect or" the heat-treatment can be attained in a single step,that is, quenching only, while the hereto lmown heat-treatment of metalsgenerally consists out two steps, that is, quenching and tampering.

Another object of this invention is to obtain a li aid to be used iorheat-treatment as the cooling medium in which heated metals arequenched.

A further object of this invention is to olotaiu a eoolingmedium whichcan keep itsernulsive condition without requiring any subsequentagitation while heated metals are losing quenched therein.

the lrnown heat-treatments of metals, properly heated metal is quenchedin either water, oil or a mixture of water and Oll, but quenching efiectis so violent that an article fit for ready use can be scarcely obtainedwithout subjecting the treated metal to a subsequent treatment calledtempering.

l or instance, when a spring for vehicles made oil carbon-steel platesor rod is quenched in either water, oil or the mixture, themicrostructure obtained is martensite or the like, and unlit tor aspring. Therefore the spring has to be subjected to ire-heating at atempering temperature of 400 'U.-500 G. in order to moderate the,violent effect oi the quenching, whereby'the proper strength andtoughness of the spring are obtains the mixture of water and oil isused, it is required to be continuously stirred while the article isbeing quenched therein because the two substances are ready to separatefrom each other. Moreover, water, when mixed with oil, takes the form ofcomparatively large particles, and large vapour bubbles are formed whenthe particles touch the highly heated surface of metal, resulting in anuneven eiiect of heat-treatment, which often causes cracks in thematerial. These drawhaclrs can be removed by this invention.

The main feature of this invented process lies in the fact that a singleheat treatment is generally suficient for the purpose, fully utilizingthe effect of the treatment in accordance with the kinds and uses of thematerial, and homogeneous substance can be obtained without the leastdanger of spoiling the article. The process can be applied on a largescale as well as a small scale with the same results.

According to this invention, a mixture of water and oil is used as thecooling medium in heat-treatment, but the oil to be used for thispurpose is limited to mineral oil such as machine-oil, cylinder oil orheavy oil as mixed with petrolene of from 0.5% to 10%, which has beenextracted from petroleumpitch with a solvent such as benzine ortetrachloride of carbon. The quantity of water to be mixed with oil isdetermined in accordance with the kind and use of the metal, and

the mixture should be suficiently agitated until it makes an emulsion.

7! hen this cooling medium is used for heat treatment, the violenteffect by water is moderated by the addition of oil, and as the waterparticles are very fine and are evenly distributed in the medium, thevapour bubbles which may be produced on the surface of the heated metalare very small, and the effect of heat treatment is uniform over thewhole surface, so that thermal strain in the article is minimized, andsprings can obtain properly balanced rigidity, tenacity and toughnessand tools a superior cutting quality,

The main characteristic of this invention. is that the cooling mediumkeeps its emulsive condition for along time requiring no subse quentagitation after it has been once emulsilied. This is due to the use ofmineral oil as mixed with petrolene from 0.5% to 10%. Since no agitatingapparatus such as pumps or propellers is required, the process can beapplied with the same result on a large scale as well as a small one.

The invention may be further explained by way of the following examples.

1. A spring for vehicles made of spring steel plates or rod containingcarbon of 0.6 to 0.88% is heated up to 800 C.830 (3., and

till

is quenchefi in a cooling mefium at a izempep:

ature of :09 0., the composition of the medium being of Water and 80% ofmachine oil containing 3% patrolene, emulsified by 5 means ofcolloid-mill. With only Ono quenching, a good sprin of troossic-swbitostrucfiure having 47-53 Shore hardness} is obtain-eel 2. bit made ofhigh-speeci tool-she! containing 0.9% carbon, 20.3% tungswn and somegoercentage of cobalt and chromil heated 1350" G, and is quenched incooling medium fibs tempemim a t the composition of the medium of Waterand 70% of machino oii 5% petroiene. '"ihs bit thus ob easily a high-*"ga-nesa 161 contains 14.0%

- 2 and has been quencheii i mm osi 38 7 this process not only fuel andlabour can be sovedT, but fahermo-cmcking and. loss of material cambeavolofid, which may be causai by repeafisd heating.

What claim is 1. process of he z izrea'meni, of metals, comm'isingquenching the heafied metals ina medium comprising emulsion of "3151 aminerofi um moi mom mg an emulsion of conmnmg 8.6% in oil conisaining"0.5% $0

